The present invention relates to a moving position detector for a coordinate input device for moving to an optional location a cursor that is displayed on a display of an information processor unit such as a computer for performing an input operation.
Recently, software has widely been used which uses the GUI (graphical user interface) for inputting data into a computer, and in conjunction with this tendency, also increasingly used as an input unit is a pointing device such as a mouse, joystick, impact tablet, and track ball. In particular, the mouse is practically widely used owing to its excellent operability.
With the recent miniaturization of personal computers and the advent of notebook-sized personal computers, however, a conventional mouse has been found relatively too large and causing inconvenience of carrying and this has given rise to the need of a smaller and thinner mouse.
A conventional mouse uses a normal ball, and the roll of the ball on the floor surface is converted into rotations of a rotary encoder by virtue of a frictional force and the number of rotations of the encoder is then detected for conversion into an output signal to a computer, whereby an input operation is effected.
A method is proposed as used in a conventional position detector for attaining its object without using any ball in which the rotation of a cylindrical rotating body, such as one disclosed in the official gazette of Japanese Patent Publication No. 2554999, Japanese Unexamined Patent Publication (Kokai) No. Sho. 60-225929 or Japanese Unexamined Patent Publication (Kokai) No. Sho. 50-96246, generated by virtue of friction between an outer circumferential (rim) portion of the rotating body and the floor surface is transferred to an encoder where it is converted into rotations thereof, and in which the number of rotations of the encoder is detected and converted for input of a moving
FIG. 14 an explanatory view showing an embodiment disclosed in the aforementioned official gazette of Japanese Patent No. 255499. In this embodiment, a rotating body 30 and a rotary encoder 37 are secured to a shaft 33 held by a bearing 32 inclined to an inclination angle at which an outer circumference of the rotating body 30 comes into contact with a floor surface 31 at a single point thereon. In a device disclosed therein, when the bearing 32 is moved in a direction normal to an inclined face of the shaft 33, the rotating body 30 rotates by virtue of friction against the floor surface 31, and the number of rotations of the rotary encoder 37 which rotates as the rotating body rotates is detected by a sensor 38 and the number of rotations so detected is converted into an input signal for use in input. The lack of frictional force at the rotating body 30 is complemented by using an attraction force from an upper ring magnet 35 and a lower ring magnet 36 or any other suitable mechanism. However, a conventional mouse is constructed such that the rotation of a ball is converted into rotations of two shafts disposed in longitudinal and lateral directions so as to be brought into contact with the ball, the rotations so converted are then converted into rotations of an encoder that is fixed to the rotating shafts, and that the number of rotations of the rotary encoder is then detected and converted into a moving distance signal. With this construction, in order to maintain the sensitivity, the ball needs to have a certain weight and be treated so as to have a high friction coefficient on the floor surface thereof, and therefore this poses a limit to efforts to make it lighter in weight and thinner in thickness. In addition, in the case of the conventional ball-type mouse, the diameter of the rotary encoder must be smaller than that of the ball, and therefore when trying to make the ball smaller, there is also encountered a limit to accuracy.
Furthermore, the ball-type mouse has drawbacks that it easily takes up dust on the floor surface or that it suffers slippage or halt in function resulting from it being easily affected by the state of the contact floor surface or dust-containing interior, this leading to a failure in accurate input of data.
On the other hand, in position detectors disclosed in the official gazettes of Japanese Patent No. 2554999 and Japanese Unexamined Patent Publication (Kokai) No. Sho. 60-225929, both examples need to have a bearing for holding inclined rotating body and rotary encoder, and this requires that the mouse needs to have a certain size in a height direction of the rotary encoder and the bearing, this construction also making it unsuitable for the realization of the thinner construction.
Moreover, as to input units other than the mouse, since they provide no intuitive input operation, practice is required to operate them smoothly, thus operational problems being caused by those input units. As to the mouse itself, there have been developed, for instance, mice for effecting signal conversions using no ball but an optical or radio system. They have, however, drawbacks that such a system makes the construction complicated and that a product so designed and manufactured becomes expensive.
An object of the present invention is to provide a moving position detector suitable for a mouse light in weight and thin in thickness.
Another object of the present invention is to provide a moving position detector suitably for use as a computer mouse that is lightweight in construction and relatively thin compared to a conventional mouse.
The invention described herein relates to a moving position detector for a coordinate input device for use in inputting a position on a display of a display device for an information processor unit comprising a rotating body adapted to rotate around a shaft normal to a floor surface, having a shaft identical to the shaft and placed such that a bottom thereof is brought into contact with the floor surface and having a pressurizing point for applying a load to a location other than the center of the bottom by gravity or by means of a mechanism element, a rotary encoder portion adapted to rotate together with the rotating body, a rotation detecting means for detecting the number of rotations of the rotary encoder portion and an output means for outputting a signal corresponding to an output from the rotation detecting means.
Another aspect of the present invention relates to the invention as set forth in herein, further comprising a pair of rotating bodies, wherein pressurizing points of the rotating bodies are disposed on the floor surface, when operated, at positions normal to each other such that one of the pressurizing points is disposed in a longitudinal direction relative to shafts while the other is disposed in a lateral direction.
In one embodiment, a lever is used to pressurize the pressurizing point so that there is caused difference in pressure at points (4a, 4b, 4c, respectively) on the bottom of the rotating body. A friction-reducing roller is provided on the lever at a portion corresponding to the pressurizing point so as to reduce friction at the pressurizing point.
In another embodiment, a ball is used to pressurize the pressurizing point so as to press the rotating body down against the pressurizing point by gravity while rotating at a certain position.
In another embodiment, a magnet and a ring are used to pressurize the pressurizing point so as to generate a force to press down the rotating body by virtue of attracting forces of the magnet and ring.
The rotating body and the rotary encoder fixed to the shaft are held by either a bearing on a lower plate of a main body or a bearing on an upper plate of the main body, with the rotating body being brought into contact to the floor surface at the bottom thereof
With any of the above embodiments, when the lower plate of the main body is placed on the floor surface, the bottom of the rotating body comes into contact with the floor surface. Applied to the points (4a, 4b, 4c) on the bottom are pressures produced by the gravity of the rotating body and the rotary encoder and applied from the pressurizing point. At this moment, although the pressure from the gravity is uniform, due to the pressure from the pressurizing point, the pressure applied to the point (4a) close to the pressurizing point becomes greater than the pressure applied to the point (4b) close to the shaft, and the pressure applied to the point 4c far away from the pressurizing point becomes lower. Due to this, when the shaft is moved in a direction normal to a line connecting the shaft to the pressurizing point, there is caused a difference in frictional force at the points (4a and 4c) with a frictional force at the point (4b) being intermediate between those at the points (4a and 4c), whereby the rotating body is allowed to rotate by virtue of a moment produced by such a difference in frictional force.
The rotation of the rotating body so produced is then eventually detected by the rotation detection means and a signal is outputted from the output means to the computer, thus a position input being effected.